Aluminum oxycarbide composition and production method therefor

Abstract

Provided is an aluminum oxycarbide composition production method capable of increasing a yield of Al4O4C while reducing a content rate of Al4C3 and achieving high productivity, and an aluminum oxycarbide composition. The method comprises: preparing a blend substantially consisting of a carbon-raw material having a mean particle diameter of 0.5 mm or less and an alumina-raw material having a mean particle diameter of 350 μm or less, wherein a mole ratio of the carbon-raw material to the alumina-raw material (C / Al2O3) is in a range of 0.8 to 2.0; homogeneously mixing the blend to allow a variation in C component to fall within ±10%; and melting the obtained mixture in an arc furnace at 1850° C. or more.

Description

TECHNICAL FIELD[0001]The present invention relates to an aluminum oxycarbide composition usable as a ceramic or refractory material, or a raw material therefor, and a production method for the aluminum oxycarbide composition.BACKGROUND ART[0002]As an aluminum oxycarbide, the following two types: Al2OC and Al4O4C, have been known. In particular, Al4O4C is stable at high temperatures and excellent in oxidation resistant, corrosion resistance and thermal shock resistance, so that it is expected as a refractory or ceramic material, or a raw material therefor. Especially, Al4O4C is expected as a raw material for a carbon-containing refractory material, such as an alumina-carbon based refractory material or a magnesia-carbon based refractory material, used as a refractory material for use with molten metal such as molten iron or steel.[0003]As a production method for Al4O4C, a sintering process of heat-treating a carbon-raw material and an alumina-raw material in a burning furnace, or a m...

AI Technical Summary

Benefits of technology

[0016]In the production method disclosed in the Non-Patent Document 1, the produced composition is in the form of a powder having a particle diameter of 10 to 100 μm. In other words, this method is incapable of producing a dense and high-strength composition. This causes a problem that versatility as a raw material for refractory materials is limited. Specifically, the composition cannot be use as a raw material for a course particle fraction having a particle diameter, for example, of 1 mm or more, so that it is impossible to sufficiently bring out advantageous effects of Al4O4C, i.e., low thermal expansion coefficient and excellent corrosion resistance. Moreover, the production under an argon atmosphere involves a problem of poor productivity.

[0017]In the production method disclosed in the Patent Document 1, a refractory aggregate having a total carbon content of 3.0 mass% or more is not suitable as a refractory raw material, because it is likely to form Al4C3 which easily reacts with water. This means that the production method disclosed in the Patent Document 1 has a problem that Al4C3 is formed as a by-product.

[0018]In the production method disclosed in the Non-Patent Document 2, Al4C3 is also formed as a by-product. Moreover, although a theoretical formation rate of Al4O4C to be calculated from a rate of raw materials used therein is 100%, it is actually 57% as calculated from C component of the sample A-7 in the Table. Thus, there is another problem of low yield of Al4O4C.

[0019]Even if Al4C3 is contained in a refractory material only in a small amount, it forms Al (OH)3 through a hydration reaction, called “slaking”, which gives rise to a phenomenon that a microstructure of the refractory material breaks up. Thus, in cases where the composition in the Non-Patent Document 2 is used as a raw material for a refractory material, a microstructure of the refractory material becomes brittle due to cracks, which causes a problem of significantly lowed strength. Specifically, there is a problem that Al4C3 develops a hydration reaction with moisture in the air during storage of the refractory material, and thereby cracks occur in the refractory material, resulting in deterioration of durability. Particularly, it is often the case that a refractory brick is stored in the air for several months, i.e., is placed in an environment where Al4C3 is more likely to undergo slaking, i.e., react with moisture in the air, for a long period of time. Moreover, the composition in the Non-Patent Document 2 cannot be used for a monolithic refractory material necessary to use water.

[0020]Production methods disclosed in the Patent Documents 2 and 3 are based on a sintering process as with the production methods disclosed in the Non-Patent Document 1, so that thee is a problem that a raw material having a dense microstructure and a large particle size cannot be obtained.

[0021]It is therefore an object of the present invention to provide an aluminum oxycarbide composition production method capable of increasing a yield of Al4O4C while reducing a content rate of Al4C3 and achieving high productivity, and an aluminum oxycarbide composition.

Problems solved by technology

As a production method for Al4O4C, a sintering process of heat-treating a carbon-raw material and an alumina-raw material in a burning furnace, or a melting process of melting a carbon-raw material and an alumina-raw material in an arc furnace, are being studied, although they have not been put to practical use.

It is also mentioned that, when the aggregate was applied to a refractory material, hot bending strength was significantly and undesirably deteriorated.